You might as well use Parthian or Sasssanid figures for Armenians, depending on the period of the army.
Illyrians are a bit more of a problem (I have been discussing a range with a few people). Early in their period, the Hoplites may be wearing "old fashioned" bell cuirasses and some of these would pass over to the Warriors as the hoplites modernised. The Illyrians were subject to influences from Italy as well as the Balkans. You could try (if you want to spend the money) mixing bodies from the Victrix armoured Samnite box with heads from their hoplite box. Shields could be hoplons from the hoplite box, scuta from their Rome's Allies box or shields from the Samnite box. As you go later in the period you can use some chainmail figures as well.

"No one ever achieved anything without making a few mistakes along the way"